1. Field of the Invention
The invention relates to a molding construction and to a molding method for a resin-molded product formed by insert molding using a primary molded product as an insert.
2. Description of the Related Art
An electronic control unit (ECU) has electronic control circuits and various electronic components mounted on a printed circuit board that is disposed in a casing made of synthetic resin. Japanese Unexamined Patent Publication No. 2000-159084 and FIG. 7 herein show examples of an ECU. The ECU shown in FIG. 7 has a box-shaped casing 1 with an open top. It should be noted that FIG. 7 shows the molding of the casing 1 and depicts the casing 1 in an inverted orientation. A circuit board 2 is disposed in the casing 1 and a circuit board connector 3 is arranged at a side wall for connection with an external mating connector. Terminal fittings 4 are mounted in the connector 3 and extend through a terminal draw out part 5 of the connector 3 for connection with the circuit board 2
The casing 1 is formed by insert molding with the circuit board connector 3 as an insert. The molding is carried out using upper and lower molding dies uk, dk that can open and close relative to each other. The circuit-board connector 3 has a bottom wall 6a and side walls 6b that cooperate with the molding dies uk, dk to prevent resin from flowing into the draw-out part 5.
The circuit board connector 3 is placed in the lower die dk. As a result, the rear side and the upper side (lower side in FIG. 7) of the terminal draw-out part 5 of the circuit-board connector 3 are closed by the lower die dk. A stepped recess 7 is formed at the highest part of the lower die dk and the bottom wall 6a of the connector 3 is nested in close contact with a corner of the recess 7. A filling space 8 is defined between the upper die uk and both the bottom wall 6a of the connector 3 and part of the lower die dk when the dies uk, dk are closed. Molten resin flows into the filling space 8, as shown by arrows in FIG. 7, and solidifies to form a bottom plate 1a of the casing 1.
The rear end of the bottom wall 6a of the connector 3 is placed closely in the corner of the recess 7 of the lower die dk to define a cutoff portion at the bottom plate 1a of the casing 1. The molten resin may flow from the filling space 8 into the cutoff portion, and may leak into the terminal draw-out part 5 of the connector 3 if the cutoff portion is not held securely in close contact.
The present invention was developed in view of the above problem and an object thereof is to prevent the leakage of resin from a cutoff portion.